Hitherto, in general, coated tools in which the surfaces of tool bodies made of tungsten carbide (hereinafter, referred to as WC)-based cemented carbide, titanium carbonitride (hereinafter, referred to as TiCN)-based cermet, or a cubic boron nitride (hereinafter, referred to as cBN)-based ultra-high pressure sintered material (hereinafter, collectively referred to as a tool body) are covered with a Ti—Al-based layer of complex nitride as a hard coating layer through a physical vapor deposition method are known, and it is known that these coated tools exhibit excellent wear resistance.
However, although the coated tool coated with the Ti—Al-based layer of complex nitride in the related art has relatively excellent wear resistance, in a case of using the coated tool under high-speed intermittent cutting conditions, abnormal wear such as chipping easily occurs. Therefore, various suggestions for an improvement in the hard coating layer have been made.
For example, Japanese Patent Application Publication No. 2012-20391 discloses that excellent wear resistance and fracture resistance are obtained, by a surface-coated cutting tool, in which a hard coating layer is formed on a surface of a tool body, the hard coating layer is configured with one layer or multiple layers, in a case where a thickness of a thinnest portion of the hard coating layer is set as T1 and a thickness at a point separated from a cutting edge ridge line by 1 mm in a cutting face direction is set as T2 in a section obtained by cutting at a specific plane, T1<T2 is satisfied, in a case where a point separated by a distance Da from the cutting edge ridge line in the rake face direction is set as a and a point separated by a distance Db in a flank direction is set as b on a surface of the hard coating layer, Da and Db satisfy a specific numerical value range, and deviation of a crystal orientation of crystal grains configuring the hard coating layer is equal to or more than 5 degrees and less than 10 degrees, in a region of the hard coating layer from the point a to the point b which is equal to or more than 10% of a region E occupying thicknesses 0.1 Ti to 0.9 Ti from the surface.
Japanese Patent Application Publication No. 2011-516722 describes that by performing chemical vapor deposition in a mixed reaction gas of TiCl4, AlCl3, and NH3 in a temperature range of 650° C. to 900° C., a (Ti1-xAlx)N layer in which the value of the amount x of Al is 0.65 to 0.95 can be deposited. However, this literature is aimed at further coating the (Ti1-xAlx)N layer with an Al2O3 layer and thus improving a heat insulation effect. Therefore, the effects of the formation of the (Ti1-xAlx)N layer in which the value of the amount x of Al is increased to 0.65 to 0.95 on cutting performance are not clear.
In addition, for example, Japanese Patent Application Publication No. 2011-513594 suggests that the heat resistance and fatigue strength of a coated tool are improved by coating a TiCN layer and an Al2O3 layer as inner layers with a (Ti1-xAlx)N layer (x is 0.65 to 0.90 in terms of atomic ratio) having a cubic structure or a cubic structure including a hexagonal structure as an outer layer, and applying a compressive stress of 100 to 1100 MPa to the outer layer.